Condensed photophonographic sound record



Feb. 14,'1933. B. E. ELDRED CONDENSED PHOTORHONOGRAPHIC SOUHD RECORD Original Filed Jan. 9, 1928 INVENToR BYRON E. ELDRED l ATTORNEY hama Fea-14, 1933 UNITED STA morn. ELDBED, oir-NEW Yonx, N. Y., Assieivon 'ro mimo oonrona'rioiv or v manica, A conrona'rroiv oil- ..Dnnnwann OONDENBEP PHOTOPHONOGRAPHAIC SOUND Urigin'al application med January 9, 1928, Serial lo. 245,634.. Divided and this application led December 24, 1930. Serial No. 504,6.V

My present invention relates to an improved photophonographic sound record. The object of this invention is to produce a record of a light sensitive material such as y 5 the usual photographic film or plate, this record being of such minute proportions that a singleline of the recorded variations will take up but little'space, andthus allow the printin of man lines thereof within a small space,t us pro ucing in another way a very much more condensed speaking book described in my application Serial N o. 716,296, filed May 28, 1924, Patent 1,734,248 of November 5, 1929.

A further object of this invention is to provide a sound recordof microscopic proportions in accordance with the method set forth in application Serial No. 245,634, filed January 9,1928, of which this present application is a division. A

The ordinary record as produced by means including the usual slit of the prior art, is not as suitable for optical reduction to produce minute scale small records, such as are required for the practice of my present invention.

To carry out this invention, I produce a primemaster record of any desired scale by the use of the method described in said prior application, Serial No. 716,296. This method removes mechanical limitations on slit size andv permits utilization of suilicient light in -recording so'thatit becomes possible to make use of comparatively fine grain slow speed emulsion ilm. For the same reason, this method allows of the production of a longer scale record by moving the primary recording lfilm at a greater rate of speed at the time of recording. -As will be evident, -this permits 'recording of higher frequencies and therefore a reater percentage of the actual vibration o` 'theoriginal sound that is to be recorded. f l

` Such primary record made withsuilicient light optically projected upon the recording film can be made remarkablysharp, dense and of high contrast, whereby it is peculiarly adapted for photographic reduction to proi duce condensed recordspof the minute scale I require for the practice of this invention.

-These records I l. produce by -the added step of optical reduction as described in my copending application Serial No. 166,622. Optical reduction of suchl rime master records of the uality produced Vin accordance with my app ication Serial N o. 180,378, Patent 1,655,811 of January 10, 1928, may be photographically reduced to greater advantage than recording direct at slow speed because the moving ofthe rimary recording iilm at slow even speed is iilicult mechanically.'

My present invention thus includes a method of making a condensed photophonographic record of sound which includes first recording sound by means of light varied in accordance with sound wave variations, concentrating said light upon a suitable aperture of relativelylarge size whereby.l a selected portion of said light is allowed to pass and the remainder stopped out, and further reducing by camera 4means whereby an image of the aperture, reduced to desired' size, is proJected on a recording lm; then moving said film at desired speed to produce a relatively large scale primary record of the sound variations, and then utilizing said record thus produced moving at a speed slower than the recording speed to project a minute image of said record on a ilm moving atan exactly proportional, still lower speed.`

The above and other features of my invention may be more fully understood from thel following 'description in connection with the accompanying drawing, in which;

Fig. 1 is a diagrammatic view of the recorder; and

F ig. 2 is a section on the line 2-2, Fig. 1, showing in detail a slot construction that `may be employed; and

Referring to Fig. 1, the recording proj ectorI A closing tube 1, containing a lamp 2, which may be any vacuum lamp of the type now well known in the art as capable of varying its radiation by and in accordance with sound variations. The sound variations and the keep alive current may be supplied from any suitable transmitting apparatus through the wires 3, 4. In the rear of the lamp 2 the casing 1 may be closed in by a reflector 5. The light, either direct or reflected, is centered by a lens 6, which in this case is shown as double convex. Beyond the focus where the converging rays cross and in a plane where a reduced image of the lamp will be formed, 1 arrange the slotted diaphragm 7 whichcuts out as much of the image and light from lamp 2 as may be desired. The light which passes through the slot is Arurther concentrated by the reducing lens 6a and a final reducing lens 8. rlhe film 9, supplied from and moved by reels 10, 11, is guided in a predetermined plane by suitable support 12. rlhe plane of the :tace of the ihn may be'as near as desired to the focal or crossing point of the rays from lens 8, but referably in a plane where a real image of t e slot is formed.

lt will be noted that I have not attempted to follow the divergence, convergence and crossing points of the light through the slot 7a of diaphragm 7, but have taken the eX- treme lines of the image of the lamp as indicating the cones and focuses characteristic of said image.

Vlt will be evident that the nearer the receiving surface of film 9 is to the focus of lens 8, the more concentrated the light'will be. Consequently, it may be desirable to utilize the well known expedient of screens for absorbing the heat rays in the beam and the light may of course be stopped down by diaphragms to any desired extent.

`While my inventionA permits the use of a slotlarge enough to avoidmechanical diculties in its production, one arrangement usable for this purpose is diagrammatically indicated in Fig. 2. Here the diaphragm comprises circular screens 13, 14, which are.

semi-circles except for the slot space 7a be tween them. Spacers 15, -16 of any desired thickness may bev employed, against which the screens may be forced to insure proper spacing and parallelism of the slot edges. The slot may be stopped down if desired by segmental pieces 18, 19, which may be also positioned by spacers 20, 21.

Referring now to Fig. 3, l produce the submaster, reduced sized records preferably by optical reduction means well known in the art by apparatus also Well known and in use 1n the motion picture art. As shown, the apparatus comprises means for moving the prime master lm record 9 in the direction shown at a speed of S feet per second. Means are also provided for moving the film 22be- Leanser' ing reproduced in an'opposite direction ata speed of SX D2 D1 feet per second. The light source 23 is proof duplication in reduced sizevas it will -be obvious that the original or prime master record may be used as a control for varying the illumination of a slit,\thus taking the place of a microphone as generally used in recording, providing means whereby the submaster record may be made of any desired size on slow speed non-grain film, as the timing factor-ot exposure is under the control of the operator and does not limit the permitted slowness of ilm travel speed as when recording the original sounds. As indicated in Fig. 4, the lines recorded on the lm as at 9a, 9b, 9c, etc., may be very narrow and the records consist of transversely parallel graduation; of shadings. There may be many parallel-lines of record, the number and closeness of their spacing being limited by the practical considerations, an. important one o which would seem to be the minimum width of space that is necessary to. insure that one record will not encroach upon the other in recording, and to insure that in reproducing the images of all but one line of record will be cut out. As the iilms are liable to a certain amount of contraction, eX- pansion, and distortion in the development,

and by varying temperatures and moistures" when in use, this may prove an important limitation.

With respect to the arrangement of the successive lines of recording upon the film 9, it is obvious that it may be convenient to record in strips alternately in opposite directions as when the ilm is reeled first in one direction and then in the other, but it will be evident that any suitable or well known form of record material may be utilized.

Having thus described my invention, attention is called to the fact that various modications may be made coming within its scope, and that I am therefore not to be limited b the specific embodiment shown and described for the purpose of illustration but by the actual scope of my invention as indicated in the appended claims.

ll claim:

l. A photophouographic record of sound comp g a sound track of microscopic dimensions.

. 2. A photo honographicy sound record comprising a and of transparent material having a photophonographic sound track of microscopic dimensions thereon.

e 3. A photographic record of sound comprisin a sound track recognizable `only by the ai of a microscope.

4. A photo honographic sound lrecord comprising a band of transparent material having a multilicity of adjacent sound tracks ,recogniza 1e only by the aid of a microscope. l

5. A sound record comprising a record carrier having a photophonographic sound track thereon so small that its characteristics are distinguishable only by the aid of a micro- Scope' BYRON E. ELDRED. 

